Segment and Related Information - Narrative (Details)	12 Months Ended
	Dec. 31, 2024 banking_Office segment office
Segment Reporting Information [Line Items]
Number of reportable business segments | segment	3
Tompkins Insurance Agencies Inc
Segment Reporting Information [Line Items]
Ownership percentage by parent	100.00%
Ithaca, NY
Segment Reporting Information [Line Items]
Number of banking offices	12
Genesee Valley Region
Segment Reporting Information [Line Items]
Number of banking offices	14
Counties North of New York City
Segment Reporting Information [Line Items]
Number of banking offices	12
Southeastern Pennsylvania
Segment Reporting Information [Line Items]
Number of banking offices	16
Western New York
Segment Reporting Information [Line Items]
Nature of operations, number of offices | office	4